A stator-cover unit of the type named above has become a common component in the meantime and is used in modern internal combustion engines for motor vehicles. The stator-cover unit is part of a camshaft adjuster. It is used for actuating a camshaft or the cam attached to the camshaft. Gas exchange valves in an internal combustion engine can be actuated by the cams. The control times of the gas exchange valves can be set selectively by means of the arrangement and shape of the cams. Adapting the valve opening times by means of a camshaft adjuster allows the efficiency of the internal combustion engine to be increased. This produces, in particular, performance gains and/or fuel savings. For this reason, more and more improvements in this field are desired.
A camshaft adjuster typically includes a stator, a locking cover, a rotor positioned in the stator, and a sealing cover. The stator is locked in rotation with a crankshaft in the installed state, while the rotor is locked in rotation with a camshaft. The stator is typically constructed with at least one vane contact surface on which the vanes of a rotor are stopped in the installed state. Overall, the use of a camshaft adjuster allows a targeted rotation of the camshaft relative to the stator in a predetermined angular range. Thus, the phase position of the cam relative to the crankshaft can be changed within certain limits.
To be able to hold the stator and the rotor in an optimal position, especially when starting or idling an engine, a slot is typically formed within the locking cover. The slot is used for the rotationally fixed locking of the rotor, wherein a piston engages in the slot, so that the stator-cover unit is connected mechanically with a positive-fit connection to the rotor. Accordingly, high forces act on the slot in the locked state.
In U.S. Pat. No. 6,311,654 B1, a camshaft adjuster is disclosed with a stator-cover unit of the type named above. The stator-cover unit is produced in multiple parts, wherein the stator is connected by means of a bolt to a locking cover constructed as a sealing plate. A rotor is inserted into the stator-cover unit. The stator and the rotor can be fixed relative to each other by a piston engaging in a slot. The slot is formed as an annular depression in the housing base of the locking cover. In this depression, after the production of the locking cover, a conically tapering ring is pressed in as a separate insert part. The piston can engage in this ring, in order to lock the stator with the rotor.
A disadvantage in such a stator-cover unit, however, is the relatively high production and assembly expense. The required hardness and stability for locking the rotor and stator can be guaranteed by an insert part.